We plan to define the mutations in human GM1 gangliosidosis, especially patients with the adult form and Morquio Type B. We will pinpoint the mutation in canine GM1 gangliosidosis (Portuguese water dogs) after completing the characterization of the normal canine acid beta-galacto- sidase cDNA. We will express canine and human acid beta-galactosidase cDNA's in several vector systems as a prelude to gene therapy. We plan to assess whether vector-transgene deliver to mutant cells can express sufficient enzyme to achieve metabolic correction and to quantify the amount of enzyme per unit time necessary to achieve this result.